Reflecting electric lamp



Aug. 25, 1959 E, B. MYERS REFLECTING ELECTRIC LAMP 3 Sheets-Sheet 1 Filed March 16, 1955 ATTORNEYS Aug. 25, 1959 E. B. MYERS 7 5 REFLECTING ELETRIC LAMP v Filed March e, 1955 I 3 Sheets -Sheet 2 55' V G INVENTOR D I so I- I ELMAN B. MYERS ATTORNEYS Aug. 25, 1959 E. B. MYERS & 5

- REFLECTING ELECTRIC LAMP Filed March 16, 1955 3 Sheets-Sheet 3 FIG.7

70 INVENTOR ELMAN B. MYERS ATTORNEYS United States Parent O REFLECTING ELECTRIC LAlVIP Elman B. Myers, Pompton Lakes, NJ., assignor to Scarborough Associates, Inc., New York, N.Y., a Corporation of New York Application March 16, 1955, Serial No. 494,742

14 Claims. (Ci. 313-113) My invention relates generally to electrc incandescent lamps of the self-contained reflecting type adapted to project a heam of light; and more particularly to improved lamps of this type which are shatter-proof, and to techniques for fabricating such lamps.

In my copendng application Serial No. 404,042 filed January 14, 1954, now Patent No. 2,818,521 issued Dec. 31, 1957 there is disclosed a lamp wherein a light emitting element of predetermined shape is so combined with a Mangin reflector as to produce a beam of light of such character that a well defined, uniformly illuminated image of the light generating element is developed without objectionable scattering or glare at a predetermined distance from the lamp. Thus, where it is desired to create an illuminated area of rectangular configuration at a given distance from the head light of an automobile, a rectangular incandescent element of the same proportions is combined with a Mangin mirror so as to project a beam of light producing a suitably enlarged rectangular image of the element at the desired distance.

It is a principal object of the present invention to provide an improved lamp of the general type disclosed in my copcnding application and to provide novel techniques for fabricating such lamps.

More particularly, it is an object of my invention to provide a self-contained lamp which is shatter-proof and insulated from mechanical and thermal Shock. A significant feature of the invention resides in the use of a shatter-proof Window which is coupled to the Mangin mirror by means of metal bellows. Another feature of importance is a glass to metal bond formed between said bellows and the glass elements coupled thereto, said bond being of exceptional thermal and mechanical strength.

Another object of the invention is to produce a tipless lamp, that is one wherein the evacuation is efiected and the lamp vacuum-sealed without means of a conventional glass tip, or metal tip.

Still another object of the invention is to provide a lamp which projects an expanded image of the filament, and wherein the filament position relative to the optical elements of the system is readily adjustable from the exteror of the lamp to enable an operator to resolve the maximum obtainable candle power at a specified distance, that is to say from about three feet from the lamp to the limit of the light source and thereby provide a maximum of obtainable efficiency in light projection.

Yet another object of the invention is to provide a selfcontained lamp of the above-described type which includes a water cell to effect continuous cooling of the lamp, thereby providing a light source of high luminous intensity and sharply reduced heat output. A liquid cooled lamp of this type is of particular value in stage and television lighting applications.

A further object of the invention is to provide an improved technique for producing a glass to metal seal. An important feature of the invention resides in the use Pa'tted Aug. 25, 1959 ice of a colloidal glass powder which is held in suspension in an Organic protective agent preventing agglomeration of the particles. The colloidal glass powder, because of its particle size and its dispersion in the protective agent, reduces to a molten glass form in such a short interval of time that the glass surface to which the metal is being bonded never reaches a temperature suificent to melt it, or which would in any way impair its optical or mechanical characteristics.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description thereof to be read in connection with the accompanying drawing, wherein like elements in the several views are identified by like reference numerals.

In the drawing:

Fig. 1 is a central horizontal sectional view of one embodiment of a sealed-in lamp assembly in accordance with the invention.

Pig. 2 is a top plan View of the structure shown in Fig. l.

Fig. 3 is a central horizontal sectional 'View of another preferred embodiment of a sealed-in lamp assembly in accordance with the invention.

Fg. 4 is a plan View of the lamp shown in Fig. 3.

Fig. 5 is a central horizontal sectional View of still another embodirnent of my invention including a liquid cooling cell.

Fig. 6, A- H, shows a variety of filamentary members for use as light emitting sources in conjunction with the lamps shown in Fgs. 1 to 5.

Fig. 7 is a sectional view of an electronic bonding apparatus for sealing tipless ribbon-ray lamps in vacuum.

Referring now to the drawings and more particularly to Fgs. l and 2, one embodirnent of the lamp assembly comprises a Mangin mirror, generally designated -by numeral 10, Secured at its periphery to one end of a cylindrical metal shell 11, the other end of the shell being enclosed by a transparent window plate 12 to form an evacuated chamber containing a light emitting element 13. Shell 11, which is preferably made of spun chrome iron, is turned inwardly `at either end to 'form bellows Ha and 11b, respectively, a glass-to-metal seal being efiected between bellows lla and mirror 10 and between bellows 11b and plate 12.

Mangin mirror 10 comprses a glass lens having polished front and rear surfaces lila and 1017, respectively, which are spherically curved. The front surface lila is curved about the focus of the lamp as a center and has a smaller radius of curvature than the rear surface, whereby the lens has the shape of a diverging menscus, thicker at its edges than at its center. The rear surface mb of the lens is mirrored, as with a silver layer 20 so as to cause the reflection of light therefrom. 'Ihe outer surface of the silver layer 20 may be covered with a protective paint or .pl-astc film. The Mangin mirror so formed acts upon light waves incident thereto, both by refraction and reflection to create a true image. By properly selecting the curvature of the front and end surfaces of the lens, the latter acts to correct incident light rays against distortion, such as spherical and chromatic aberration, astigmatism 'and Coma. Moreover, when a light emitting element is placed at a focal point with respect to the Mangin mirror, a sharply defined image thereof is produced and lateral light spreading is relatively slight `as compared with that produced by a parabolic reflector.

The Mangin mirror 10 is provided with a central opening 14 from which there is projected an air exhaust tube 15 to pernt evacuation of the lamp. -Suitable apertures are formed on either side of opening 14, through which v 3 aperture filament support leads 16 andvl7, preferably Element 13 is formed of incandesciblematerial, such as tungsten, and is preferably of a rectangular shape.. The element 13 is arranged at a foc al point with respect to the Mangin mirror for projecting the image of the element at a .predetermined distance'frorr the mirror. One of the faces of rectangular element 13 is directed toward the mirror and is disposed perpendicularly with respect to the optical axis of the mirror. The Outline of element 13 corresponds with that of the area to be illuminated. For example, if an area cf rectangular shape having a large length relative to width is to beilluminated, as is ordinarly desired with a motor vehicle head-light, the element should be of like rectangular shape, Using light emitting elements of other shapes, sharply `define ill-uminated areas having corresponding shapes may be projected at a desired distance from the lamp.

The focal position of element 13 with respect to the reflector determines the distanceat which a sharp, clear image of the element is produced. Such. focal distance also, establishes the horizontal and vertical angles of `divergence of the projected light beam and accordingly the size of the area illuminated at a predeterrnined distance. But the light pattern of the illuminated area is always that produced by the particular shape of the light emitting element and there is no appreciable illumination beyond this area. Within the pattern, the illumination is substantially uniform, the edges of element 13 ,giving ofi very little light. To increase the fiatness of ,the image of light producing element 13, the element may be curved with a radius of curvature substantially equal to the radius of curvature of the refiecting surface 20, the conveX side of the element being directed toward the concave side of the reflecting surface.

In one method of assembling the foregoing lamp, we start With the chrome iron shell 11. The inwardly tapered inside lips of bellows 11a and 111) at either end of shell 11 are sprayed with a glass solder, preferably in the form of Coming powdered glass solder No. 7570, ground to 325 mesh and Suspended in bentonite. The Contacting or adhering edges of Mangin mirror 10and window plate 12 are also sprayed with glass solder. T he mirror 10 and the window plate 12 are preferably made of G-8 llime glass, both being case hardened. It is noted that shell 11 is (further provided with a circumferential bead llc.

Shell 11 is then placed in a graphite holder with the bellows 11b in a downward position. The circular edge of window plate 12 is tapered to complement the taper on the lip of bellows 11b and is nested in position within the bellows. The graphite holder is now put on a revolving spindle. Pin point heating fires are arranged to heat up 'the region of the chrome iron shell in contact with the glass plate 12 to a `desired temperature. The entire assembly is heated by an electric oven to a temperature of 50 below the critical annealing point of the glass plate. The pin point fires are then turned on to heat the shell to a point at which the glass solder melts and by so doing produces a hermetic bond of glass to metal. The Connector caps 18 and 19 and the exhaust tube are sealed ;by this same procedure. Thereafter the Mangin mirror 10 is sealed to bellows lla of the shell in the same manner, pin point fires being directed to the region of contact between the mirror and the bellows.

It is to be noted that the Coming glass solder No. 7570 has the correct coeflicient of expansion to accommodate the characten'stics of expansion of the G-8 glass and chrome iron. The resulting seal is one of mechanical 4 compression and it provides the greatest strength obtainable for both thermal and mechanical shock. It is also important to recognize that :the case hardened condition of the window plate 12 is unafiected by the sealing operation and that the important optical surfaces of the Mangin mirror 10 are maintained. The combination of a case hardened Mangin mirror'andwindow plate in conjunction With the metal shell provides a completely shock-proof assembly with superior mechanical shock-resistant qualities for aircraft landing lights, military illuminations, television and theatre stage lighting and general vehicle use.

Referring now to Figs. 3 and 4 there is shown another embodiment of a self-contained, reflecting-type lamp, the lamp being characterized by the fact that the focus thereof is readily adjustable.

The lamp comprises a cylindrical metal shell 21 turned inwardly at either end to form single bellows 21a and 2 117. A glass window plate 22is edge-bonded to 'bellows 2161 and a Mangin mirror, generally designated by numeral 23, is bonded at its periphery to bellows 21b. Also provided is a ribbon filament 24.

As in the case of Fg. 3, Mangin mirror 23 comprises a glass lens havingpolishedfront and rear surfaces 23a and 23b, respectively, which are spherically curved. The front surface 23a has a smaller radius of curvature than the rear surface 23b, therear surface having a reecting layer 25 applied thereto so as to cause the reflection of light therefrom. The reflecting layer may be covered with a protective film. The Mangin mirror 23 is also provided centrally with a neck portion 26 to which is attached an adjustable filament mounting, generally designated by numeral 27. Filament mounting 27 includes amulti-segmented cylindrical metal bellows 28, whose ends are turned inwardly to form tapered lips, one lip being bonded to the neck 26 of the mirror, the other lip being bonded to an insulating terminal block 29, which may be made of glass. It will be noted that neck 26 and block 29'are tapered to complement the taper of the end lips of the bellows 28.

The terminal block 29 is provided withtwo spaced conical apertures through which extend filament support rods 30 and 31, preferably fabricated of molybdenum. The rods pass through bellows 28 and extend into the body of the lamp to support thefilamentary element 24, which element is welded to the ends of therods. The filament support rods 30 and 31 terminate in Connector caps 32 and 33 mounted on the glass block 29. Thus, the filament is supported from terminal block 29.

Copper brazed on either end of bellows 28 and concentric therewith, are right and left-hand rings 34 and 35 which are externally threaded. Threadably engaging rngs 34 and 35 is a focusing collar 36, the collar being constituted by two connected sections and being externally knurled to facilitate hand manipulation. Rotation of the focusing collar in one direction effects contraction of the bellows 28 and in the other' direction expansion thereof, thereby causing axal movement of the insulating block 29 and of the filament 24 mounted thereon.

The lamp may be evacuated through an exhaust tube 37 attached to the shell 21 and projecting laterally therefrom. The lamp is hermetically sealed by means of glass cement seals formed between the opposte ends of shell 21 and mirror 23 and Window plate 22, and between the opposite ends of bellows 28 and neck 26 and insulating block 29. In addition, a glass to metal seal is formed between the Connector caps 32 and 33 and the glass block 29, the caps being seated in circular grooves formed in the block. The vacuum envelope of the lamp includes the space defined by the shell 21 and the bellows 28. The molybdenum rods 30 and 31 may be attached to caps 32 and 33 by copper brazing in a hydrogen furnace and the rings 34 and 35 may be similarly brazed to the bellows 28. i

The direction of the thread on the rings 34 and 35, is in opposed relationshp, such that-upon rotation of the focusing collar 36 the rings are moved axially in reverse directions, i.e. either toward each other or away from each other, depending upon the angular direction of collar rotation. The rotation of the focusing collar effects aXial movement of the insulating block 29 and of the filament 24 supported thereby. Thus, the focus of the lamp may readly be adjusted, while maintaining the evacuated condition of the lamp. It is to be understood that the lamp may be filled with an inert gas. r

Referring now to Fig. 5, there is shown a modification of the lamp illustrated in Figs. 3 and 4, which modification includes a liquid cell to efiiect rapid cooling of the lamp and prevent the radiation of heat therefrom. In the use of lamps for stage, television and motion picture studio lighting, the problem of heat generated and resolved optically on the subject being photographed is of major concern. This problem is particularly troublesome in color motion picture taking and in color television transmission where the light requirements are of a high order. In a lamp in accordance with the invention a liquid cell is made integral with the lamp structure to provide a compact and eficent water-cooled lamp.

In Fig. 5 the lamp assembly corresponds to that shown in Figs. 3 and 4, save that a liquid cooling cell, generally designated by numeral 38, is incorporated in the lamp structure. The liquid cell comprises an auxiliary metal shell 39 which partially surrounds the front end of shell 21 and is concentric therewith. One end ofthe auxiliary shell 39 is constricted to form a rim 39a which engages the outer surface of shell 21 and is adhered thereto by means such as Copper brazed to form a water-'right seal. The front end of auxiliary shell 39 is turned inwardly to form a bellows 39b having a tapered lip to which is Secured a shatter-proof glass window 40 postioned in parallel relation with respect to the window plate 22 of the lamp and spaced therefrom to provide a water channel 41. An inlet pipe 42 is attached to one side of auxiliary shell 39 and an outlet pipe 43 is attached to the other side thereof for conducting water through channel 41. Thus, the light bean projected through window plate 22 passes through the liquid cell and is cooled thereby, the continuous flow of water serving to dissipate the heat rays. With this lamp it is possible to focus an enlarged image of the ribbon filament on any desired object, animate or inanimate, and at any required distance, substantially without heat. The entire color temperature of the white light spectrum will be resolved for color photography or color television use.

Referring now to Fig. 6, A-H, there are shown in various views five different kinds of metal filaments suitable for the projection of a luminous field when operated in conjunction with the Mangin mirror lamp assemblies illustrated in the previous figures.

Shown in elevational view in Fig. 6-A and in plan View in Fig. 6-B is a rectangular sheet filament 44 supported at its short sides by two molybdenum struts 45 and 46, the filament being energized by applying a current thereto through said struts. A filament so shaped and disposed at the focal position of the Mangin mirror will give rise to a rectangular luminous field representing a scale enlargement of the filament.

Shown in Fig. 6-C is a plan View of a corrugated or accordion-pleated type of filament 47, with wire supports 48 and 49 attached to the ends thereof. A filament so shaped will produce an enlarged scale image corresponding to a rectangle whose length is equivalent to the distance between end supports 48 and 49 and whose height equals that of filament 47. The increased filamentary area provided by the pleated filament structure makes possible greater candle power than would be obtained with a straightforward rectangular filament.

In Fig. 6 D there is shown, in elevation, a filament 50 of the rectangular ribbon type provided with end supports 51 and 52. This type is particularly suited for automobile headlights, for the resultant luminous field face change occurs in the massive glass element.

has a large azimuthal spread but is restricted in elevation to prevent objectionable glare with respect to an oncoming vehicle. Figs. 6-E and F show in elevation and plan views, respectively, a circular disc type of filament 53 with four equi-spaced metal supports 54. A filament so shaped will produce a circular luminous field particularly adapted for use as a theatrical Spotlight. Fgs. 6-G and H show a cross type of filament 55 in elevation and plan View, respectively, each branch of the filament having a suitable support 56. A filament so shaped will produce a luminous field in the form of a cross, for specialized applications.

In fabricating the self-contained reflecting type of lamps described in connections with Figures 1 to 6, it is essential that a hermetic seal be made between the associated metal shell and glass elements and that the seal be formed without optical distortion of the glass elements such as would result from melting of the glass.

In known glass to metal scaling techniques, making use of a glass powder which is coated on the surfaces of the members to be bonded, the time entailed in heating the powder to the molten form is such as to raise the temperature of the adjacent glass elements to the melting point. This causes distortion of the glass elements and impairs the optical properties thereof. In the case of a reflecting lamp, as heren described, making use of a Mangin mirror, such distortion would adversely affect the desired optical characteristics of the lamp. Moreo ver, the glass particles in powders of the type heretofore used tend to agglomerate and to heat unevenly, as a result of which blobs of glass are fonncd in the scaling process which introduces mperfections in the seal.

In accordance with the present invention, a new and improved glass scaling technique is provided involving the use of colloidal glass powder Suspended in an Organic protective agent which precludes agglomeration or coalescence of the glass particles. The glass is ground to colloidal powder sizes by known means such `as by 'ball milling for prolonged periods. Preferably, the glass is ground to colloidal particle size by means of a high-velocity impact colloid mill of the type disclosed in the patent to Myers entitled Apparatus for Disintegrating Solids, No. 2,119,887, issued June 7, 1938.

The colloidal glass powder held in suspension is sprayed on the surfaces to be sealed to form a thin layer of colloidal glass particles. Because of its minute particle size, the colloidal glass powder reduces to a molten glass form in such a short interval of time that the glass surface to which the metal is being bonded never attains a temperature suflicient to melt it. The use of 'the Organic pro-tective agent as a suspension medium serves to isolate the colloidal glass particles and to prevent agglomeration thereof.

Ammonium tannate is a preferred form of protective agent. Since this composition is an Organic hydrocarbon, it Volatalizes during the bonding operation. The colloidal glass particles are preferably in the order of minus 5 microns to minus 2 microns in size. These particles exhbit strong brownian motion when observed in a solution with a dark field microscope. 'It is important to note that the protective agent maintains particle isolation during the heating thereof, the agent being eliminated in the bonding process. Even though the glass powder may contain some relatively coarse particles, the fluxing action produced by the ultra-fine particles -accelerates the bondng process.

The bonding technique making use of colloidal glass in a suspension is operative with difierent types of glass, that is quartz, all types of Pyrex, soda lime and lead glass and vycor. It will be appreciated that with the glass scaling technique, heren disclosed, no melting occurs in the glass part being bonded and that no displacement or sur- The action that does occur is a wetting of the surface eifect of both glass and metal. v

It is desirable that the glass element being bonded be first unifonnly elevated to a temperature of about 50 below the critical annealing point thereof, this being done to avoid thermal shock. The addition-al heat which -is then applied is within a pattern, so zoned, that the resolved temperature develops in the colloidal glass powder. Visually, the eifect of colloidal glass bonding is similar to that observed when silver solder flashes over a surface when a critical temperature point is reached during a brazing operation.

The colloidal glass bonding technique can be performed in air with an open gas flame. However, a preferred procedure is to bond in vacuum using electronic induction heating methods. With uniform electric heating in vacuum no thermal Shock occurs. Here we find the ideal oven, maximum heat saturation by contact, minimum heat loss by radiation and ideal annealing. When the massive glass element has reached a temperature 50 below the critical annealing point, the bonding action is completed in a matter of a few seconds by the rapid elevation of temperature of the shell bellows to a bright red heat, whereby the wetting action of the colloidal glass follows almost instantly.

It is desirable that the glass and metal surfaces being bonded be free of foreign matter, and that the contacting surfaces be reasonably parallel to establish a uniform interfacial contact. But the Contacting surfaces may be smooth or ground. With the bonding technique, as herein disclosed, it is possible to bond a lead glass element to one end of the shell and a PyreX glass element to the other end -thereof In such circumstances, however, the colloidal powder used at the Pyrex to metal bond should be formed of Pyrex powder and at the lead glass to metal bond of lead glass powder. In other words, the colloidal glass should always match the massive glass being bonded. The technique is by no means limited to the fabrication of lamps, and it is to be understood that it may be used in any instance requiring a glass to metal seal.

Referring now to Fig. 7, there is shown a vacuum system for the fabrication of a lamp of the type shown in Figs. 1 to 6. By way of example only, a lampof the type shown in Fig. 1 is assembled by the system, the bonding of the various components being carried out in vacuum, thereby 'obviating the need for an exhaust tube -anda separate evacuaton process. e

The vacuum system includes a bell-shaped vacuum chamber 57 and a cover 58 therefor, the cover being in the form of a steel plate. The chamber is supported :in -a fixed position by vertical posts (not shown) and the cover is movable in 'the vertical direction relative to the chamber to close or open the vacuum system. The vacuum seal is efiected by a rubber ring gasket 59 set in the bottom edge of the chamber 57 and engaging the surface of plate 58. r r

The vacuum chamber may be preliminarily exhausted by a relatively small pump coupled to the chamber by a pipe 60 and controlled by a valve 61. The vacuum ,condition of the system is indcated by a vacuum gauge 62 coupled to the chamber by a pipe 63. A main diifusion pump for evacuating the chamber is coupled thereto by a pipe 69 and controlled by a valve 65. Argon gas 'may be supplied to the chamber through a pipe 66 controlled by a needle valve 67.'

Mounted on top of cover 59 is an expandible bellows 68 whose height is governed by means of air pressure applied thereto through a pipe 69 passing through cover 59`and controlled by a valve 70. Cemented to'the top of the bellows 68 is a transite asbestos disc 71.

The lamp Components to be assembled and-sealed are the glass window plate 12,1the metal shell 1 1 having end bellows 1-1a 'and 11b, the Mangin 'mirror 10, the filament support rods 16 and 17, the connector caps 18 and -19 and the filament 13.

The glass window 12 is supported-onthe asbestos disc 71, which plate upon eXpansion of the bellows 69 raises the window 12 into position within the shell bellows 11b. On either side of bellows 68 and supported on cover 58 are transite asbestos bars 72 and 73, above which are Vertically mounted guide rods 74 and 75 for channeling the upward movement of the window 12. A transite asbestos support assembly to hold the shell and mirror 10 in position is constituted by Vertical bars 76 and 77, an annular plate 84 resting on bars 76 and 77 and surrounding shell 11, and bars 78 and 79 mounted above plate 84 and engaging the lower side of shell bead 11c.

surrounding the contactor caps 18 and 19 is a first highfrequency induction coil 80, surrounding the lamp assembly in .the region of the shell bellows 11a is a second highfrequency inducton coil 81, and surrounding the assembly in the region of shell bellows 11b' is a third highfrequency induction coil 82. These coils are supported by suitable insulators (not shown) and are fed by a highfrequency supply through suitable bushings in the cover 58. The coils are of hollow tubing through which water may be circulated to carry away the heat generated 'by the flow of high-frequency current and radiant heat from the heated object.

In induction heating, the object to be heated being of metal and therefore a conductor, currents are induced within it and the resistance offered by the metal to the flow of such currents results in rapid heating. Where the metal is magnetc in nature, heating results by reason of hystereses losses.

In fabrication, the filament support assembly constituted by rods 16 and 17 are held in place by a jig fixture (not shown), and a colloidal glass powder paste, as above described, is placed in the circular grooves in mirror 10 in which the caps 18 and 19 are seated. When the chamber has reached a vacuum of tenth of the minus six millimeters pressure, the high-frequency is switched on induction coil 80 to heat the caps 18 and 19, thereby melting the glass powder to form a hermetic bond of metal caps to glass mirror.

The caps 18 and 19 having been bonded to mirror 10, the rods 16 and 17 connected thereto are now held in correct position for filament mounting. The ribbon filament 13 is placed in suitable slots in the ends of rods 16 and 17 and given a mechanical pinch. The juncture thus formed is wetted with a solution of molybdenum boride, acting as a flux, and the juncture is electrically welded. It is to be noted that the filament position for focal accuracy can be maintained to very close tolerances in mass production after the mechanical distances have been set. There is no change introduced during bonding, the only plasticity occurring in the colloidal glass powder.

The scaling of the Mangin mirror 10 and of the window plate 12. to the opposte ends of shell 11 is carried out as follows: The lips 11a and 11b of shell 11 and the complementary edges of mirror 10 and window plate 12 are coated by the colloidal glass paste. The Mangin mirror is nested within lips 11a, whereas the window plate 12 rests on asbestos disc 71, in the position shown in Fig. 7. T hus, the lamp assembly is open to its full exhaust area, to provide maximum speed in out-gassing of the filament. Now, all valves are closed, except valve 60 which is opened to permit preliminary evacuaton of the chamber. When the limiting pressure is reached, valve 60 is closed and valve 65 is then opened to permit full exhaustion of the chamber. When the limiting pressure of the difl usion pump is reached, the high-frequency is turned on coil 81, to efiect bonding of the Mangin mirror 10 with the shell bellows 11a. Whereupon the difusion pump valve 65 is closed and needle valve 67 is opened 'to admit argon gas into the chamber to the required amount. Valve 67 is then closed and valve 70 is opened 'to supply air pressure to bellows 68 sufiicient to elevate window plate 12 'into scaling contact with the shell bellows 11b. The high-frequency is then turned on in coil 83 and the -Window plate 12 *is 'thereby electronically 9 bonded to shell bellows llb. The lamp is now gas filled and hermetically sealed, without an exhaust tip or tubulation. The chamber is then returned to atmospheric pressure, the steel cover 58 is lowered and the finished lamp is removed.

It will be observed that the filament is out-gassed during exhaust and that no oxidation of lamp parts can occur during the assembly operation. The sealing is accomplished very quickly and mechanical uniformity is maintained throughout the operation.

While there has been shown what are considered to be preferred embodiments of a reflecting lamp and preferred techniques for fabricating same, it will be appreciated that many changes and modifications may be made therein without departing from the essential spirit of the invention. It is intended therefore in the appended claims to cover all such changes and modifications as fall within the true scope of the nvention.

What is claimed is:

l. A reflecting-type lamp comprising an open-ended shell having inturned end portions to form single bellows at either end thereof, each of said bellows having an annular inner lip, a refiector enclosing one end of said shell and sealed to the inner lip of the bellows thereat, a transparent closure enclosing the other end of said shell and sealed to the inner lip of the bellows thereat, and a light emitting element mounted within said enclosed shell.

2. A reecting-type lamp comprising an open-ended metal shell having inturned end portions to form single bellows at either end thereof, each of said bellows having an annular inner lip, a Mangin mirror enclosing one end of said shell and sealed at its periphery to the inner lip of the bellows thereat, said mirror having an outer reflecting surface, a window enclosing the other end of said shell and sealed at its edge to the inner lip of the bellows thereat, and a light emitting element disposed within said enclosed shell.

3. A reflecting-type lamp comprising an open-ended metal shell having inturned end portions to form single bellows at either end thereof each of said bellows having an annulular inner lip, a Mangin mirror enclosing one end of said shell and sealed at its periphery to the inner lip of the bellows thereat, said mirror having an outer reflecting surface, a window enclosing the other end of said shell and sealed at its edge to the inner lip of the bellows thereat, and a filament disposed within said enclosed shell at the focal position of said mirror to generate a light beam producng a sharply defined illuminated area.

4. A reflectng-type lamp comprising an open-ended metal shell having inturned end portions to form single bellows, each bellows having a tapered inner lip, a glass reflector element enclosing one end of said shell and sealed to the tapered inner lip of the bellows thereat, said element having a tapered periphery complemertary to the taper of the associated bellows, a glass window enclosing the other end of said shell and sealed to the tapered inner lip of the bellows thereat, said window having a tapered edge complenentary to the taper of the associated bellows and a filament mounted within said shell.

5. A reflecting-type lamp for producing a sharply-de fined illuminated area comprising an open-ended cylindrical metal shell having inturned end portions forming single bellows, each bellows having a tapered inner lip, a Mangin reflector enclosing one end of said shell and peripherally-sealed to the tapered inner lip of the bellows thereat, said reflector having a tapered periphery complementary to the taper of the associated bellows to provide a compression seal, a glass window plate enclosing the other end of said shell and edge-sealed to the tapered inner lip of the bellows thereat, said plate having a tapered edge complementary to the taper of the associated bellows to produce a compression seal, and a substantially fiat filament mounted within said shell at the focal position of said reflector and having one face thereof drected '10 toward said reflector, said flat filament being dsposed perpendicularly relative to the optical axis of said reflector.

6. A lamp, as set forth in claim 5, ment has a ribbon shape. I

7. A lamp, as set forth in claim 5 ment hasa surface corrugation.

8. A lamp, as set forth in claim 5, ment is disc-shaped.

9. A lamp, as set forth in claim S, ment is formed by crossed-ribbons.

10. A liquid-cooled refiecting-type lamp comprising a lamp structure including a main metal shell having inturned end portions forming single bellows, each bellow having an annular inner lip, a refiector enclosing the reat end of said shell and peripherally-sealed to the inner lip of the bellows thereat, a window enclosing the front end of the shell and edge-sealed to the inner lip of the bellows thereat, a light element mounted within said enclosed main shell; and an integral water cell including an auxliary shell surrounding the front end of said main shell and extending forwardly therefrom, the rear end of said auxiliary shell being bonded to said main shell, a second window enclosing the front end of said auxiliary shell to define a water channel between said windows to remove heat rays from the light beam projected therethrough.

11. A lamp, as 'set forth in claim 10, wherein the front end of said auxiliary shell is inturned to form a single bellows, and wherein said second window is edge-sealed thereto.

12. A liquid-cooled refiecting-type lamp comprising a lamp structure including a main metal shell having inturned end portions forming single bellows, each bellow having an annular inner lip, a reflector enclosing the rear end of said shell and peripherally-sealed to the inner lip of the bellows thereat, a window enclosing the front end of the shell and edge-sealed to the inner lip of the bellows thereat, a light element mounted within said enclosed main shell; and an integral Water cell including an auxiliary shell surrounding the front end of said main shell and extending forwardly therefrom, the rear end of said auxilary shell being bonded to said main shell, a second window enclosing the front end of said auxiliary shell to define a water channel between said windows to remove heat rays from the light beam projected therethrough, said lamp further including means controllable from the exterior of said lamp to adjust the position of said lighting element along the optical axis of said reflector.

13. A reflecting-type lamp comprising a metal shell having inturned front and rear portions to form single bellows, each bellow having an annular inner lip, a Mangin reflector enclosing the rear of said shell and sealed to the inner lip of the bellows thereat, a window enclosing the front of said' shell and sealed to the inner lip of the bellows thereat, said reflector having a central neck portion projecting therefrom, a multi-segmented bellows device mounted on said neck and sealed at one end thereto, an nsulating block enclosing the other end of said device and sealed thereto, filament supporting wires mounted on said block and extending through said bellows device and said neck into said shell, and exterior means to compress and expand said bellows to adjust the position of said filament along the optical axis of said refiector.

14. A lamp, as set forth in claim 13, wherein said exterior means to control said bellows device includes conversely threaded rings concentric with said device and secured thereto at either end, and a collar surrounding said bellows device and threadably engagng said rings whereby rotation of said collar effects expansion or contraction of said bellows device.

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